In order to avoid giving patients discomfort provoked by an endoscope used for observing the state of the patients' internal organs, virtual endoscopy has been developed and widely and usefully used with respect to a bronchus, a blood vessel, a large intestine, a joint, and so on in a human body. In virtual endoscopy, an image similar to a real endoscopic image is generated using a series of two-dimensional images collected through CT or MRI. In other words, a virtual endoscope is noninvasive and thus allows the inside of a patient's internal organs to be observed without giving the patient pain, so recently, it is very usefully used.
A real endoscope allows the inside of internal organs to be observed only in a direction in which a camera moves. Unlikely, a virtual endoscope allows a user to observe the inside of internal organ in desired directions and is thus very helpful to diagnosis.
However, a conventional virtual endoscope is difficult to operate due to inefficient user interface.
For example, a conventional virtual endoscopic method is composed of a two-dimensional reference image acquired using an image input apparatus and a virtual endoscopic image generated from the two-dimensional reference image. Accordingly, in the conventional virtual endoscopic method, a correlation between the reference image and the virtual endoscopic image is two-dimensionally shown, so it is difficult to express a three-dimensional correlation and detect the position of a part shown in the virtual endoscopic image or a relative relation with other structures.
In the conventional virtual endoscopic method, a virtual camera is controlled and expressed in a two-dimensional reference image. Accordingly, it is difficult for a user to operate the virtual camera in a desired direction and recognize the direction of the virtual camera.